% help file, orbfit 3.1 and later
% this is the main menu of the fitobs main

MAIN MENU

From this menu all the functionalities of FITOBS are accessed.

1 = input of observational data ...is performed automatically at
startup, but can be redone if the observation file(s) have been
changed and/or the selection flags have been modified.

2 = acquire orbital elements ...is performed automatically at startup,
but can be redone to go back to the values of the orbital elements
supplied from the catalogues. If orbital elements are not available,
they can be computed from 3 observations by Gauss' method.

3 = differential corrections ...to improve the orbital elements by
least square fit to the observations. Note that some first guess is
needed to start; menus 2 and 4 can be used.

4 = first guess for identification ...to identify two sets of
observations as belonging to the same asteroid/comet, some first guess
for the common orbital elements is required before going to menu 3.

5 = state propagation ...available orbital elements can be brought
forward/backward to some other epoch, by an accurate N-body
computation.

6 = predictions of observations ...for a given set of orbital
elements, the observations can be predicted at any given time,
together with their uncertainties. Also simulated observations
can be used in simulated orbit improvement.
  
7 = multiple solutions ...for an object observed only over a short
arc, the solutions compatible with the observations cannot be
described by the confidence ellipsoid, but form a nonlinear set.
Close approach analysis is now included in this menu.
  
8 = coordinate change... the currently available orbital elements are
converted to some other coordinates; choice between CAR, KEP, EQU,
COM, ATT. The converted elements are written in the astname.fel file,
in the MultiLine format.

9 = attributables... computed from the observations of one of the two arcs;
they can also be used to generate preliminary orbits.

10 = status ...show all the status
flags, showing which data are available at a given stage of the
computation; also the initial condition and observation epochs.
 
11 = date conversion ...from calendar to MJD.

0 = exit ... stop FITOBS